The February 22nd 2006 bombing of one of Shiite Islam’s holiest shrines, the Golden Mosque in the town of Samarra, sparked considerable retaliatory killing as 2 of the 12 imams revered by mainstream Shiites, including the 11th imam, Hassan al-Askari, are buried there. Legend has it that he 12th Imam, was at the site of the shrine before he disappeared. 

The core of the Shi’ite religious world view is the Hidden Imam, Muhammad al-Mahdi, “The Guided One.” While the stories of the first eleven Imams are historical in nature, the history of the twelfth Imam is mystical and miraculous. Born in 868 AD / 255 AH, Abu’l-Kasim Muhammad (which is the name of the Prophet himself), and when Hasan al-Askari, the Eleventh Imam, died in 874 AD / 260 AH, the seven year old boy declared himself to be the Twelfth Imam and went into hiding. The Shi’ites believe that he hid himself in a cave below a mosque in Samarra; this cave is blocked by a gate which the Shi’ites call Bab-al Ghayba , or the “Gate of Occultation.” This is one of the most sacred sites in Shi’a Islam, and the faithful gather here to pray for the return of the Twelfth Imam.

The central Shi’a doctrines revolving around the Hidden Imam are the doctrines of Occultation (Ghayba) and Return (Raj’a) . The Doctrine of Occultation is simply the belief that God hid Muhammad al-Mahdi away from the eyes of men in order to preserve his life. God has miraculously kept him alive since the day he was hidden in 874 AD / 260 AH; eventually God will reveal al-Mahdi to the world and he will return to guide humanity…

The Hidden Imam, however, will eventually leave his Greater Occultation and appear (zuhur) to the world of humanity. This return is the most significant event in the future for the Shi’ite faithful and has thunderous eschatological consequences. This return will occur shortly before the Final Judgment and the end of history. Imam Mahdi will return at the head of the forces of righteousness and do battle with the forces of evil in one, final, apocalyptic battle. When evil has been defeated once and for all, the Imam Mahdi will rule the world for several years under a perfect government and bring about a perfect spirituality among the peoples of the world. After the Imam Mahdi has reigned for several years, Jesus will return (raj’a).

The Holy Prophet Muhammad (SAW) has prophesied about several events that will occur just before the advent of the Day of Judgment.  Among these, the last prophet has foretold the advent of one of his descendants, Al Mahdi (the guided one), which will materialize when the believers are severely oppressed in every corner of the world.  He will fight the oppressors, unite the Muslims, bring peace and justice to the world, rule over the Arabs, and lead a prayer in Mecca at which Isa – Jesus will be present”. 

http://en.shafaqna.com